Slice thinly using a mandolin or rotary cutter. The thicker you cut, the longer they take to dry and they may be slightly chewy instead of thin and crisp. I use my rotary cutter with a slicing blade that makes them nearly perfectly thin, but not toooo thin.
In a large mixing bowl, add sliced zucchini and/or cucumbers, sprinkle the salt over top, and toss to coat well. Allow to sit for 20-30 minutes so the slices release their water. I have found this step leads to crisper chips and shorter drying times.
After resting, drain the zucchini slices in a colander, tossing so they drain, but not worrying about getting them completely dry.
Add slices back to the bowl, add the balsamic vinegar, and toss to coat. Let slices sit for 15 minutes.
Step 2: Dehydrate
Layer zucchini or cucumber slices in a single layer on a dehydrator tray lined with a mesh liner if desired.
Place trays in your dehydrator and set at 135F for 10-18 hours, or til the slices are crisp and appear dry with no signs of moisture. They should snap easily in half with your fingers and not be too bendy.
If using a bottom fan dehydrator, rotate trays during the cycle. If using a back fan dehydrator, like my Magic Mill, you don't need to do that.
Step 3: Storage
Allow chips to cool for about 15-20 minutes after drying and then fill glass mason jars and vacuum seal. They will store on the shelf about 1-2 years, especially if you add oxygen absorbers, but I can barely make them last a week in this house!
Notes
If it is very humid when you're pulling them out of the dehydrator, work quickly because the chips will take on moisture readily and this will dramatically affect their shelf stability.